diff --git a/controller_interface/CMakeLists.txt b/controller_interface/CMakeLists.txt
index 7486ee3414..62dbad2381 100644
--- a/controller_interface/CMakeLists.txt
+++ b/controller_interface/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.5)
 project(controller_interface)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  add_compile_options(-Wall -Wextra)
+  add_compile_options(-Wall -Wextra -Wconversion)
 endif()
 
 find_package(ament_cmake REQUIRED)
diff --git a/controller_manager/CMakeLists.txt b/controller_manager/CMakeLists.txt
index 53999d4f70..cb4150c17d 100644
--- a/controller_manager/CMakeLists.txt
+++ b/controller_manager/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.5)
 project(controller_manager)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  add_compile_options(-Wall -Wextra)
+  add_compile_options(-Wall -Wextra -Wconversion)
 endif()
 
 set(THIS_PACKAGE_INCLUDE_DEPENDS
diff --git a/hardware_interface/CMakeLists.txt b/hardware_interface/CMakeLists.txt
index 5892f0c3b3..d4091d63c9 100644
--- a/hardware_interface/CMakeLists.txt
+++ b/hardware_interface/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.5)
 project(hardware_interface)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  add_compile_options(-Wall -Wextra)
+  add_compile_options(-Wall -Wextra -Wconversion)
 endif()
 
 set(THIS_PACKAGE_INCLUDE_DEPENDS
diff --git a/hardware_interface/src/component_parser.cpp b/hardware_interface/src/component_parser.cpp
index 7792b0fbf4..e087d39c95 100644
--- a/hardware_interface/src/component_parser.cpp
+++ b/hardware_interface/src/component_parser.cpp
@@ -348,7 +348,8 @@ ComponentInfo parse_complex_component_from_xml(const tinyxml2::XMLElement * comp
     component.command_interfaces.push_back(parse_interfaces_from_xml(command_interfaces_it));
     component.command_interfaces.back().data_type =
       parse_data_type_attribute(command_interfaces_it);
-    component.command_interfaces.back().size = parse_size_attribute(command_interfaces_it);
+    component.command_interfaces.back().size =
+      static_cast<int>(parse_size_attribute(command_interfaces_it));
     command_interfaces_it = command_interfaces_it->NextSiblingElement(kCommandInterfaceTag);
   }
 
@@ -358,7 +359,8 @@ ComponentInfo parse_complex_component_from_xml(const tinyxml2::XMLElement * comp
   {
     component.state_interfaces.push_back(parse_interfaces_from_xml(state_interfaces_it));
     component.state_interfaces.back().data_type = parse_data_type_attribute(state_interfaces_it);
-    component.state_interfaces.back().size = parse_size_attribute(state_interfaces_it);
+    component.state_interfaces.back().size =
+      static_cast<int>(parse_size_attribute(state_interfaces_it));
     state_interfaces_it = state_interfaces_it->NextSiblingElement(kStateInterfaceTag);
   }
 
diff --git a/joint_limits/CMakeLists.txt b/joint_limits/CMakeLists.txt
index 314ec67272..52f2044e19 100644
--- a/joint_limits/CMakeLists.txt
+++ b/joint_limits/CMakeLists.txt
@@ -7,7 +7,7 @@ if(NOT CMAKE_CXX_STANDARD)
 endif()
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  add_compile_options(-Wall -Wextra)
+  add_compile_options(-Wall -Wextra  -Wconversion)
 endif()
 
 find_package(ament_cmake REQUIRED)
diff --git a/transmission_interface/CMakeLists.txt b/transmission_interface/CMakeLists.txt
index 1a51bbb3e8..a2cf4d7884 100644
--- a/transmission_interface/CMakeLists.txt
+++ b/transmission_interface/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.5)
 project(transmission_interface)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  add_compile_options(-Wall -Wextra -Wpedantic)
+  add_compile_options(-Wall -Wextra -Wpedantic -Wconversion)
 endif()
 
 set(THIS_PACKAGE_INCLUDE_DEPENDS